1. Field of the Disclosure
The present disclosure relates generally to fuser designs, and more particularly to an endless fuser belt assembly having two metal rolls and two heating elements.
2. Description of the Related Art
In an electrophotographic image forming device such as printers and copiers, toner is applied and developed to form a toned image. A fuser assembly in the apparatus then adheres the toned image to a surface of a media such as paper. Fusing methods may be in the form of a radiant fusing, convection fusing, and contact fusing. The most common form of which is contact fusing, which involves two fusing members pressed against each other to form a fusing nip, with one of the fusing members being heated. Heating one of the fusing members may either be in the form of having a heating element disposed on an inner portion on one of the fusing member or external thereto. Various arrangements of fuser assembly components for adhering toned image to media sheets are widely known in the art.
Common market requirements considered in designing fuser assemblies include fast fusing speed, short warm-up and first print time, good narrow media performance, long life, and low cost. Yet it is often the case that at least one of those requirements may be compromised to meet another.
For example, in order to obtain a fast fusing speed, at least one of these methods may be employed for a belt fuser assembly: (1) make the fuser belt thinner, (2) widen the fusing nip, and (3) apply greater load to the fusing nip. Although a thinner belt may result in shorter warm-up and first print times, the resulting axial heat transfer capability and narrow media performance of is low. In particular, when running narrow media, the portion of the fusing nip where no media passes heats up quickly, oftentimes exceeding the desired fusing temperature of the fuser assembly, which either shortens the lifetime of the fuser belt and/or the backup roll or requires lower fusing speeds.
In an alternative design where the fuser assembly components are enlarged to achieve a larger fusing nip region, the speed to which the fuser belt operates may be relatively faster. Yet, increasing the size of the fusing nip also increases the warm-up time and first copy time, the thermal mass of the system, and the size of the whole fuser assembly, which is undesirable. In yet another design, applying greater load to the fusing nip may translate to faster fusing speed. However, more robust components are required such that manufacturing costs for the fuser assembly are increased.